1. Field of the Invention
The present invention relates to a vehicle headlamp of a projector type, employing a semiconductor-type light source to illuminate light to a forward direction of a vehicle by switching a light distribution pattern having one or more cutoff lines (light distribution pattern for low beam, light distribution pattern for passing) and a light distribution pattern for high beam (light distribution pattern for cruising).
2. Description of the Related Art
A vehicle headlamp of this type is conventionally known (Japanese Laid-open Patent Application No 2007-109493, for example). Hereinafter, a conventional vehicle headlamp will be described. The conventional vehicle headlamp is made up of a first light source unit forming a light distribution pattern for low beam; and a second light source unit forming a light distribution pattern for high beam. The first light source unit is a projector-type lamp unit, and is provided with: a light source (light emitting diode); an elliptical (convergent) reflector; a shade; and a projecting lens. In addition, the second light source unit is a projector-type lamp unit, and is provided with: a light source (light emitting diode); an elliptical (convergent) reflector; and a projecting lens. Hereinafter, functions of the conventional headlamp will be described. When the light source of the first light source unit is lit, the light emitted from the light source is reflected by means of the reflector; a part of the reflected light is cut off by means of the shade; a light distribution pattern having an oblique cutoff line and a horizontal cutoff line, i.e., a light distribution pattern for low beam is formed; and the light distribution pattern for low beam is longitudinally and transversely inverted from the projecting lens, and illuminated (projected) to a forward direction of a vehicle. In addition, when the light source of the second light source unit is lit, the light emitted from the light source is reflected by means of the reflector, and the reflected light is longitudinally and transversely inverted from the projecting lens, and is illuminated (projected) toward the forward direction of the vehicle, as a light distribution pattern for high beam.
Again, the conventional vehicle headlamp is made of: the first light source unit having the light source, the reflector, a shade, and the projector lens; and the second light source unit having the light source, the reflector, and the projector lens. Thus, the conventional vehicle headlamp requires a large number of components and the second light source unit for a light distribution pattern for high beam, and entails problems concerning downsizing, weight reduction, power saving, and cost reduction, accordingly.
The projector-type vehicle headlamps of this kind, using power discharge bulbs, halogen electric bulbs, metal halide lamps, or light source bulbs as light sources, are conventionally known (Japanese Laid-open Patent Application Nos. 2002-324413 and 2000-215717 and Japanese Laid-open Utility Model Application No. 63-111704, for example). However, the conventional vehicle headlamps use power discharge bulbs, halogen electric bulbs, metal halide lamps, or light source bulbs as light sources, thus allowing light from the light sources to be radiated in a direction of 360 degrees with respect to a reference axis (optical axis, reflecting surface axis, lens axis). Therefore, the conventional projector-type vehicle headlamps provide reflecting surfaces (reflectors) for reflecting the radiated light from the light sources in the direction of 360 degrees with respect to the reference axis, thus increasing spaces for constituent elements, and entails downsizing as in the above-described conventional vehicle headlamp.
The present invention has been made to solve problems concerning downsizing, weight reduction, power saving, and cost reduction, which could arise due to the fact that the conventional vehicle headlamp requires the second light source unit for a light distribution pattern for high beam.